Professional Surveyor March 2008 Volume 28 Number 3
Editor's Desk: GPS Is Everywhere
Tom Gibson, PE
On a weekend cross-country ski trip in early February, I ventured to Lapland Lake Nordic Vacation Center in New York's Adirondack Mountains, a complex with 50 kilometers of trails that wander in circuitous routes. I skied with my friend Pete, who carries a handheld GPS receiver strapped to his backpack. As we navigated the trail network, we would come to an occasional critical intersection, and he would say, "let me take a reading on this." Then at the end of the day, after he punched a button or two on the receiver, he announced that we had skied 12 miles.
This shows how prevalent GPS and satellite positioning have become. It permeates the surveying world more all the time and takes a parallel path in the civilian arena as well (more and more cars are equipped with GPS navigation functions). This issue focuses on satellite positioning just for this reason. Construction companies increasingly use machine control in their earthmoving operations. Aerial mapping companies are adopting airborne GPS, as we detailed in our Aerial Mapping 2008 supplement. Satellite constellations continue to increase in number and size, as Galileo and Glonass take shape, and we also hear about China's Compass Navigation Satellite System and one being built by India. RTK GPS surveying continues to see increased use as it becomes more affordable for surveyors, and base station networks proliferate around the world.
In January, I got a good glimpse of this when I attended the Pennsylvania Society of Land Surveyors' Surveyors Conference 2008. Brian Naberezny, a surveyor pursuing his Ph.D. at Penn State, taught a session entitled "Static GPS Post Processing." I thought it might be an esoteric class on math and software algorithms, but it turned out to be a complete historical overview of GPS and satellite positioning. Did you know it all started when the Russians launched Sputnik in 1957? Scientists at Johns Hopkins University noticed that radio signals received from the satellite varied based on its position. They measured Doppler shifts and used these to calculate Sputnik's position, theorizing that if the satellite position is known, they could compute positions on Earth.
But this issue also focuses on another area experiencing rapid technological advancement: subsurface surveying. Surveyors have long used magnetic locators to locate buried markers and underground pipelines as a means to an end in doing their job. Now, with the advent of ground-penetrating radar, they can take on the actual mapping of our underground infrastructure. This becomes more important as this expands while parts of existing infrastructure decay and need upgrading and replacement. As our infrastructure grows, it becomes more advantageous to map it in 3D and not just have plan-view layout drawings of it. GIS plays a huge role in creating a geospatial picture of this.
On a more immediate note, yours truly experienced a hard drive crash in his computer recently and lost all the data on it (it suffered what they call a head crash, and I joke that it wasn't wearing its helmet). I had backed up my document files but not my email. So if any of you have been corresponding with me by email, either about contributing a future story or to send me information on your company, please get back in touch with me so nothing falls though the cracks. And yes, I have since learned how to back up my email.
lunes, 12 de mayo de 2008
What is a "corner" ?
Professional Surveyor March 2008 Volume 28 Number 3
Rules of the Game: What is a corner — Really?
Donald A. Wilson, LLS, PLS, RPF
My previous article began a discussion of Griffin's Rules based on his treatise, Retracement and Apportionment as Surveying Methods for Re-establishing Property Corner (Marquette Law Review, 43: 484-510). The article also centered around corners: lost verus obliterated, and the important court case Rivers v. Lozeau regarding property corners. The word "corner" should always be emphasized in the land surveyor's mind, since the corner is what retracement, and sometimes apportionment, is all about. So, exactly, what then is a corner?
Looking first at a definition, a corner has been defined by the court system as the intersection of two converging lines or surfaces; an angle, whether internal or external; the "corner" of a building, the four "corners" of a square, the "corner" of two streets. A mere variation in a line does not constitute a "corner" (Christian v. Gernt. et al., Tenn. Ch., 64 S.W. 399 [1900]).
The lay definition, according to Webster's New Collegiate Dictionary, also sometimes relied on by the courts, has been stated as "the point or place where two converging lines, sides, or edges meet; angle. Also, a piece designed to form, occupy, mark, protect, or adorn a corner of anything."
"A boundary corner is the point of intersection of two boundary lines; a marker is a physical object either placed or adopted by someone to call attention to the corner."
Thus, many equate a marker to a corner, when often it is not. A boundary corner is the point of intersection of two boundary lines; a marker is a physical object either placed or adopted by someone to call attention to the corner. A marker may or may not occupy the position of the corner. In fact, some markers have no relationship to any corners, but occasionally they are accepted as evidence based on an assumption that they do mark the corner(s). Horseshoe pins, mailbox posts, and burial markers for pets all fall into this category. In addition, an accessory may have been placed nearby a corner not intending to be at the location of the corner but to be a witness to a corner and indicate where the corner is located. Other property corners also act as witnesses to a corner in addition to true "witness corners." Some things that are just that, corners, which may or may not be property corners. Some examples are building corners, street corners, and fence corners.
As stated in 12 Am Jur 2d Boundaries, § 61, "On a resurvey to establish lost boundaries, if the original corners can be found, the places where they were originally established are conclusive without regard to whether they were in fact correctly located, in this respect it has been stated that the rule is based on the premise that the stability of boundary lines is more important than minor inaccuracies or mistakes. But it has also been said that great caution must be used in reference to resurveys, since surveys made by different surveyors seldom wholly agree. A resurvey not shown to have been based upon the original survey is inconclusive in determining boundaries and will ordinarily yield to a resurvey based upon known monuments and boundaries of the original survey."
The Ohio court recognized this point in the case of Sanders v. Webb (85 Ohio App.3d 674, 621 N.E.2d 420 [1993]) wherein it was stated, "the law provides that the original corners established during the progress of the survey shall forever remain fixed in position, and that even evident errors in the execution of the survey must be disregarded where these errors were undetected prior to the sale of the lands. The original monuments thus assume extreme importance in the location of land boundaries. Unfortunately, most of the public lands were surveyed before the present day regulations relative to the character of monuments went into effect, and as a consequence most of the monuments used were of a very perishable nature. Their disappearance or destruction has rendered the relocation of old lines a very difficult task."
Several courts have not only emphasized the philosophy, or directive, but have made it clear that anything other than locating an existing line placed by a surveyor (whether marked or not) is outside of the surveyor's responsibility when surveying (locating) a boundary. In fact, the court stated in Pereles v. Gross (126 Wis. 217 [1905]) that anything other than locating the original, existing, line may be unlawful: "In resurveying a tract of land according to a former plat or survey, the surveyor's only function or right is to relocate, upon the best evidence obtainable, the corners and lines at the same places where originally located by the first surveyor on the ground. Any departure from such purpose and effort is unprofessional, and, so far as any effect is claimed for it, unlawful."
Now that many of the original markers have disappeared, the courts are interested in where they were and where they were set when the points were established. The Utah court so stated in Home Owners' Loan Corporation v. Dudley et al. (141 P.2d 160 [1943]): "The original location of a monument controls, and, if it is obliterated, the court is concerned in ascertaining where it was originally located."
And in the case of what is known as a nonexistent corner, the Colorado court stated, "A corner which has never existed cannot be said to be lost or obliterated and established under the rules relating to the establishment of lost or obliterated corners, but should be established at the place where the original surveyor should have put it" (Lugon v. Crosier, 240 P. 462, 78 Colo. 141 [1925]). The court elaborated by saying that "if the monument were lost or obliterated there would be some reason to attempt to re-locate it." However, "when it is a myth, never on the ground, the natural, straight-forward and sensible way is to establish the corner at the place where the original surveyor ought to have put it."
As previously noted, the words "corner" and "marker" are frequently used interchangeably, when they should not be. A marker merely calls attention to the corner; it may or may not be at the same location as the corner itself. Finding a marker is but half the answer; it then remains to be proven what relationship it has to the corner, if any. Granted, markers set by the original surveyor may be corners, but also may not be, depending on what and where they are.
The BLM Manual addresses this point:
"The terms "corner" and "monument" are often used largely in the same sense, though a distinction should be noted to clarify the difference. The term corner denotes a point determined by the survey process, whereas a monument is the physical structure erected for the purpose of marking the corner point upon the earth's surface" (Bureau of Land Management Manual of Instructions, 1947, § 349).
Additionally, a corner may also be a mathematically determinable point, such as where markers were never set, although title lines and corners have been established and recognized. This was an issue for the Washington court in 1931: The center of a section is not a physical government monument, but it is a point capable of mathematical ascertainment, "thus constituting it, in a legal sense, a monument call of the description" (Matthews v. Parker, 299 P. 354, 163 Wash. 10).
Corners and monuments are not the same, although under the right conditions, they both may be at the same point. Surveyors have to decide when they are, and when they aren't.
About the Author
Don Wilson is president of Land & Boundary Consultants, Inc.; and part owner of and the lead instructor in Surveyors Educational Seminars, a member of the Professional Surveyor/RedVector Dream Team providing online courses for continuing education; and a regular instructor in the University of New Hampshire Continuing Education System for 25 years. He is also co-author of several well-known texts.
Rules of the Game: What is a corner — Really?
Donald A. Wilson, LLS, PLS, RPF
My previous article began a discussion of Griffin's Rules based on his treatise, Retracement and Apportionment as Surveying Methods for Re-establishing Property Corner (Marquette Law Review, 43: 484-510). The article also centered around corners: lost verus obliterated, and the important court case Rivers v. Lozeau regarding property corners. The word "corner" should always be emphasized in the land surveyor's mind, since the corner is what retracement, and sometimes apportionment, is all about. So, exactly, what then is a corner?
Looking first at a definition, a corner has been defined by the court system as the intersection of two converging lines or surfaces; an angle, whether internal or external; the "corner" of a building, the four "corners" of a square, the "corner" of two streets. A mere variation in a line does not constitute a "corner" (Christian v. Gernt. et al., Tenn. Ch., 64 S.W. 399 [1900]).
The lay definition, according to Webster's New Collegiate Dictionary, also sometimes relied on by the courts, has been stated as "the point or place where two converging lines, sides, or edges meet; angle. Also, a piece designed to form, occupy, mark, protect, or adorn a corner of anything."
"A boundary corner is the point of intersection of two boundary lines; a marker is a physical object either placed or adopted by someone to call attention to the corner."
Thus, many equate a marker to a corner, when often it is not. A boundary corner is the point of intersection of two boundary lines; a marker is a physical object either placed or adopted by someone to call attention to the corner. A marker may or may not occupy the position of the corner. In fact, some markers have no relationship to any corners, but occasionally they are accepted as evidence based on an assumption that they do mark the corner(s). Horseshoe pins, mailbox posts, and burial markers for pets all fall into this category. In addition, an accessory may have been placed nearby a corner not intending to be at the location of the corner but to be a witness to a corner and indicate where the corner is located. Other property corners also act as witnesses to a corner in addition to true "witness corners." Some things that are just that, corners, which may or may not be property corners. Some examples are building corners, street corners, and fence corners.
As stated in 12 Am Jur 2d Boundaries, § 61, "On a resurvey to establish lost boundaries, if the original corners can be found, the places where they were originally established are conclusive without regard to whether they were in fact correctly located, in this respect it has been stated that the rule is based on the premise that the stability of boundary lines is more important than minor inaccuracies or mistakes. But it has also been said that great caution must be used in reference to resurveys, since surveys made by different surveyors seldom wholly agree. A resurvey not shown to have been based upon the original survey is inconclusive in determining boundaries and will ordinarily yield to a resurvey based upon known monuments and boundaries of the original survey."
The Ohio court recognized this point in the case of Sanders v. Webb (85 Ohio App.3d 674, 621 N.E.2d 420 [1993]) wherein it was stated, "the law provides that the original corners established during the progress of the survey shall forever remain fixed in position, and that even evident errors in the execution of the survey must be disregarded where these errors were undetected prior to the sale of the lands. The original monuments thus assume extreme importance in the location of land boundaries. Unfortunately, most of the public lands were surveyed before the present day regulations relative to the character of monuments went into effect, and as a consequence most of the monuments used were of a very perishable nature. Their disappearance or destruction has rendered the relocation of old lines a very difficult task."
Several courts have not only emphasized the philosophy, or directive, but have made it clear that anything other than locating an existing line placed by a surveyor (whether marked or not) is outside of the surveyor's responsibility when surveying (locating) a boundary. In fact, the court stated in Pereles v. Gross (126 Wis. 217 [1905]) that anything other than locating the original, existing, line may be unlawful: "In resurveying a tract of land according to a former plat or survey, the surveyor's only function or right is to relocate, upon the best evidence obtainable, the corners and lines at the same places where originally located by the first surveyor on the ground. Any departure from such purpose and effort is unprofessional, and, so far as any effect is claimed for it, unlawful."
Now that many of the original markers have disappeared, the courts are interested in where they were and where they were set when the points were established. The Utah court so stated in Home Owners' Loan Corporation v. Dudley et al. (141 P.2d 160 [1943]): "The original location of a monument controls, and, if it is obliterated, the court is concerned in ascertaining where it was originally located."
And in the case of what is known as a nonexistent corner, the Colorado court stated, "A corner which has never existed cannot be said to be lost or obliterated and established under the rules relating to the establishment of lost or obliterated corners, but should be established at the place where the original surveyor should have put it" (Lugon v. Crosier, 240 P. 462, 78 Colo. 141 [1925]). The court elaborated by saying that "if the monument were lost or obliterated there would be some reason to attempt to re-locate it." However, "when it is a myth, never on the ground, the natural, straight-forward and sensible way is to establish the corner at the place where the original surveyor ought to have put it."
As previously noted, the words "corner" and "marker" are frequently used interchangeably, when they should not be. A marker merely calls attention to the corner; it may or may not be at the same location as the corner itself. Finding a marker is but half the answer; it then remains to be proven what relationship it has to the corner, if any. Granted, markers set by the original surveyor may be corners, but also may not be, depending on what and where they are.
The BLM Manual addresses this point:
"The terms "corner" and "monument" are often used largely in the same sense, though a distinction should be noted to clarify the difference. The term corner denotes a point determined by the survey process, whereas a monument is the physical structure erected for the purpose of marking the corner point upon the earth's surface" (Bureau of Land Management Manual of Instructions, 1947, § 349).
Additionally, a corner may also be a mathematically determinable point, such as where markers were never set, although title lines and corners have been established and recognized. This was an issue for the Washington court in 1931: The center of a section is not a physical government monument, but it is a point capable of mathematical ascertainment, "thus constituting it, in a legal sense, a monument call of the description" (Matthews v. Parker, 299 P. 354, 163 Wash. 10).
Corners and monuments are not the same, although under the right conditions, they both may be at the same point. Surveyors have to decide when they are, and when they aren't.
About the Author
Don Wilson is president of Land & Boundary Consultants, Inc.; and part owner of and the lead instructor in Surveyors Educational Seminars, a member of the Professional Surveyor/RedVector Dream Team providing online courses for continuing education; and a regular instructor in the University of New Hampshire Continuing Education System for 25 years. He is also co-author of several well-known texts.
E-Myth (entrepeneur)
Professional Surveyor March 2008 Volume 28 Number 3
Book Review: The E-Myth Revisited
Jeff Salmon
At year's end I was perusing a list of "underrated business books" on the Bnet website (www.Bnet.com, devoted to dispensing business advice), when I came upon a short review of this book. (Note first that the "E" stands for "entrepreneur," not "E-Commerce" or "Electronic.")
The reason it caught my eye was the author's definition of the e-myth:
"the entrepreneurial myth that most people who start small businesses are entrepreneurs,
the fatal assumption that an individual who understands the technical work of a business can successfully run a business that does that technical work. "
Let's start with the second part of this definition, and it bears repeating: "the fatal assumption that an individual who understands the technical work of a business can successfully run a business that does that technical work." Working with small survey shops and sub-contractors I cannot help being struck by the accuracy of this observation. And if land surveyors don't qualify as "technical workers" I am at a loss for who would.
If this observation seems a bit harsh, and you as the owner/ operator of a small, technically oriented business are thrilled with the success and profitability of your shop, then by all means, skip this review.
However, if you are like many who work in small survey shops, you may have already discovered that being proficient in the technical aspects of surveying does not necessarily carry over into the other aspects of running a business.
The stakes are high: Within five years, nearly 80 percent of all newly formed small businesses will fail. The author blames the e-myth for this failure rate. As described above, the e-myth suggests that most people who start a small business are entrepreneurs. Nothing could be further from the truth; most folks who start small businesses are "technicians" whether they are land surveyors, carpenters, or beauticians.
Make no mistake: these people are great at what they do. Unfortunately, as part two of the definition points out, being a great technician rarely translates into being a great business person. I once heard it put another way: "Working 20 years for someone else does not prepare you to work for yourself."
Part One: Three Personalities
The book is divided into three major parts: part one expounds further on the concept of the e-myth and, more importantly, provides the reader with the three personalities that are necessary for a successful business: the Entrepreneur, the Manager, and the Technician.
The Entrepreneur is the visionary, dreaming up new ideas for the business. Without the Entrepreneur, the business would suffer from lack of innovation and fail to differentiate itself from the competition. The downside of the Entrepreneur is that, thriving on change, he creates havoc around him and sees most people as problems that get in the way of his vision.
The Manager's pragmatic personality, on the other hand, is all about organization. The Manager craves order and clings to the status quo. If, without the Entrepreneur there is no innovation, then without the Manager there would be no structure and therefore no business.
The Technician is, of course, the one who "gets things done." The Technician is not a dreamer, he's a doer. He finds the Entrepreneur to be a constant source of irritation, always dreaming up impractical ideas when his hands are full of practical projects that need to be done. As an individualist, he is likewise annoyed by the Manager's attempt to create structure, which he often sees as an attempt to "control" him.
The trick, the author says, is not to go out and hire an Entrepreneur and a Manager to augment the Technician in you; rather you should develop the Entrepreneur and Manager within yourself. Mr. Gerber does this by pushing the business person past his "comfort zone" into the realm of the "entrepreneur perspective."
Part Two: The "Turn-Key Business"
Here the author introduces the concept of the turn-key business by using the business format franchise as a model. Whereas, during a five-year period 80 percent of small businesses fail, the rate of failure for franchises is only 25 percent. What accounts for the success of the franchise is not necessarily the product, but rather the well-developed turn-key business system that is provided to the franchisee. To be sure, the author does not advocate turning your business into a franchise, but he does a great job of explaining how this prototype has a high success rate and provides higher-than-normal rates of return on investment.
Not surprisingly, the author of The E-Myth Revisited promotes the tools of business process management that I have discussed previously in my Business Angle column. By analyzing, improving, and most of all documenting your business processes you can begin to achieve what the author sets as a goal for all small businesses: "Working on not in your business." If you only do the later, that is work in your business, all you have created is a job, not a business. By working on your business you create an entity that is separate from yourself and doesn't require your constant attention. You can actually spend time away from your business and decrease your burnout factor.
Moreover, when you begin to think of the business as a product in itself, then you have created value that will serve you in the future. After all, one day you will want to retire. If you have worked on the business, you can sell the business. If all you've done is worked in the business, then you find no takers when you try to sell just a job.
Part Three: Business Development Concepts
In this section of the book the author introduces the "Business Development Program" that has seven steps, your:
Primary Aim
Strategic Objective
Organizational Strategy
Management Strategy
People Strategy
Marketing Strategy
Systems Strategy
Although space doesn't permit a full examination of each of these steps, I will discuss the first, and probably most important, step: "Your Primary Aim." The author makes it clear that the first step in organizing (or re-organizing) your business begins, not with your business, but with you personally. You should create a vision of how you want to live your life, who you want to be, and what you want your life to look like. "I believe it's true that the difference between great people and everyone else is that great people create their lives actively, while everyone else is created by their lives, passively waiting to see where life takes them next." The author points out that the difference between these two is "living intentionally and living by accident."
If one gets nothing more than this lesson from the book, then the book is money well spent. However, I found The E-Myth Revisited to be an eye-opening experience, not just another self-help business book. There is plenty of great advice here for the owner of a small survey shop or any technically oriented small business.
Resources
A company website, www.e-myth.com, offers more information on the concept behind the e-myth. This is a commercial site; however you can avail yourself of free newsletters and information too. Try running "Michael Gerber" through Amazon.com's search function to find this and other related books.
For more information about process management, check out the July and August 2007 issues of this magazine for a two-part article, "Process Management: The path to profitability." If you haven't saved your past issues, search the magazine's archives online at www.profsurv.com/archives.
About the Author
Jeff Salmon helps his clients with land-use and a variety of general business issues, including marketing, in Elizabeth, Colorado.
Book Review: The E-Myth Revisited
Jeff Salmon
At year's end I was perusing a list of "underrated business books" on the Bnet website (www.Bnet.com, devoted to dispensing business advice), when I came upon a short review of this book. (Note first that the "E" stands for "entrepreneur," not "E-Commerce" or "Electronic.")
The reason it caught my eye was the author's definition of the e-myth:
"the entrepreneurial myth that most people who start small businesses are entrepreneurs,
the fatal assumption that an individual who understands the technical work of a business can successfully run a business that does that technical work. "
Let's start with the second part of this definition, and it bears repeating: "the fatal assumption that an individual who understands the technical work of a business can successfully run a business that does that technical work." Working with small survey shops and sub-contractors I cannot help being struck by the accuracy of this observation. And if land surveyors don't qualify as "technical workers" I am at a loss for who would.
If this observation seems a bit harsh, and you as the owner/ operator of a small, technically oriented business are thrilled with the success and profitability of your shop, then by all means, skip this review.
However, if you are like many who work in small survey shops, you may have already discovered that being proficient in the technical aspects of surveying does not necessarily carry over into the other aspects of running a business.
The stakes are high: Within five years, nearly 80 percent of all newly formed small businesses will fail. The author blames the e-myth for this failure rate. As described above, the e-myth suggests that most people who start a small business are entrepreneurs. Nothing could be further from the truth; most folks who start small businesses are "technicians" whether they are land surveyors, carpenters, or beauticians.
Make no mistake: these people are great at what they do. Unfortunately, as part two of the definition points out, being a great technician rarely translates into being a great business person. I once heard it put another way: "Working 20 years for someone else does not prepare you to work for yourself."
Part One: Three Personalities
The book is divided into three major parts: part one expounds further on the concept of the e-myth and, more importantly, provides the reader with the three personalities that are necessary for a successful business: the Entrepreneur, the Manager, and the Technician.
The Entrepreneur is the visionary, dreaming up new ideas for the business. Without the Entrepreneur, the business would suffer from lack of innovation and fail to differentiate itself from the competition. The downside of the Entrepreneur is that, thriving on change, he creates havoc around him and sees most people as problems that get in the way of his vision.
The Manager's pragmatic personality, on the other hand, is all about organization. The Manager craves order and clings to the status quo. If, without the Entrepreneur there is no innovation, then without the Manager there would be no structure and therefore no business.
The Technician is, of course, the one who "gets things done." The Technician is not a dreamer, he's a doer. He finds the Entrepreneur to be a constant source of irritation, always dreaming up impractical ideas when his hands are full of practical projects that need to be done. As an individualist, he is likewise annoyed by the Manager's attempt to create structure, which he often sees as an attempt to "control" him.
The trick, the author says, is not to go out and hire an Entrepreneur and a Manager to augment the Technician in you; rather you should develop the Entrepreneur and Manager within yourself. Mr. Gerber does this by pushing the business person past his "comfort zone" into the realm of the "entrepreneur perspective."
Part Two: The "Turn-Key Business"
Here the author introduces the concept of the turn-key business by using the business format franchise as a model. Whereas, during a five-year period 80 percent of small businesses fail, the rate of failure for franchises is only 25 percent. What accounts for the success of the franchise is not necessarily the product, but rather the well-developed turn-key business system that is provided to the franchisee. To be sure, the author does not advocate turning your business into a franchise, but he does a great job of explaining how this prototype has a high success rate and provides higher-than-normal rates of return on investment.
Not surprisingly, the author of The E-Myth Revisited promotes the tools of business process management that I have discussed previously in my Business Angle column. By analyzing, improving, and most of all documenting your business processes you can begin to achieve what the author sets as a goal for all small businesses: "Working on not in your business." If you only do the later, that is work in your business, all you have created is a job, not a business. By working on your business you create an entity that is separate from yourself and doesn't require your constant attention. You can actually spend time away from your business and decrease your burnout factor.
Moreover, when you begin to think of the business as a product in itself, then you have created value that will serve you in the future. After all, one day you will want to retire. If you have worked on the business, you can sell the business. If all you've done is worked in the business, then you find no takers when you try to sell just a job.
Part Three: Business Development Concepts
In this section of the book the author introduces the "Business Development Program" that has seven steps, your:
Primary Aim
Strategic Objective
Organizational Strategy
Management Strategy
People Strategy
Marketing Strategy
Systems Strategy
Although space doesn't permit a full examination of each of these steps, I will discuss the first, and probably most important, step: "Your Primary Aim." The author makes it clear that the first step in organizing (or re-organizing) your business begins, not with your business, but with you personally. You should create a vision of how you want to live your life, who you want to be, and what you want your life to look like. "I believe it's true that the difference between great people and everyone else is that great people create their lives actively, while everyone else is created by their lives, passively waiting to see where life takes them next." The author points out that the difference between these two is "living intentionally and living by accident."
If one gets nothing more than this lesson from the book, then the book is money well spent. However, I found The E-Myth Revisited to be an eye-opening experience, not just another self-help business book. There is plenty of great advice here for the owner of a small survey shop or any technically oriented small business.
Resources
A company website, www.e-myth.com, offers more information on the concept behind the e-myth. This is a commercial site; however you can avail yourself of free newsletters and information too. Try running "Michael Gerber" through Amazon.com's search function to find this and other related books.
For more information about process management, check out the July and August 2007 issues of this magazine for a two-part article, "Process Management: The path to profitability." If you haven't saved your past issues, search the magazine's archives online at www.profsurv.com/archives.
About the Author
Jeff Salmon helps his clients with land-use and a variety of general business issues, including marketing, in Elizabeth, Colorado.
Surveying technology at the Hamilton Wetlands Restoration Project
Professional Surveyor April 2008 Volume 28 Number 4
Feature: At the Forefront of Wetland Restoration
Chris Wang and Edgar Salire
Most people know that wetlands are steadily declining nationwide and that we are losing their numerous biological, ecological, environmental, and recreational benefits. California alone has seen a drastic decline caused by human-related activities. Only recently has government policy change halted further destruction of wetlands. As a prime example, several governmental agencies led by the U.S. Army Corps of Engineers, the California Coastal Conservancy, and the San Francisco Bay Conservation and Development Commission are undertaking wetland restoration on the former Hamilton Army Airfield.
The Hamilton Wetlands Restoration Project is located in the city of Novato, California, about 25 miles north of San Francisco. The former airfield was active until the early 1970s, and then in the 1990s it was closed as part of the Base Realignment and Closure Program. The area was originally a natural wetland but was diked off from San Francisco Bay waters in the late 1800s. Today, the project footprint covers 988 acres of wetlands, home to several protected species such as the clapper rail, salt harvest mouse, and the burrowing owl. The cost to restore the historical wetlands will exceed several hundred million dollars.
This project is multifaceted in that it will not only create a wetland but also recycle dredge spoils from the Port of Oakland harbor-deepening project, which is normally disposed of in a landfill or an offshore site. The dredge materials will be enclosed by a series of constructed perimeter levees, thereby creating a "bathtub" effect. Once the dredge material is imported, it will be sculpted to create a northern seasonal wetland and a southern tidal wetland. Survey instruments installed at predetermined intervals will guide the bulldozers as they sculpt the site to design elevations.
Surveying is incorporated in the design, construction, and monitoring phases of the Hamilton Wetland Restoration Project. The data collected are incorporated in civil design, hydrologic/ hydraulic design, and geotechnical engineering to document prior, existing, and future conditions. Surveying tells the story of the wetland restoration process by documenting many construction activities ongoing at any given time.
The Hamilton survey team and survey consultants have deployed a multitude of surveying technology in the forms of RTK GPS and traditional surveying. To optimize effectiveness, survey crews and remote sensing technology were deployed to complete construction activities. High-resolution orthophoto imagery was developed and used to produce a project basemap. Derived from the rectified imagery and composed of a feature map and a digital terrain model (DTM), this is a key component in making project design decisions.
Hydrologically, survey data forms a direct input into the design and has proved instrumental in developing a self-sustaining wetland design, thereby preventing short-circuiting of design water flow between the southern seasonal and northern tidal wetland. Survey contributions to geotechnical engineering have come in the form of monitoring of ground response and impact on existing infrastructures such as pipelines and residential and commercial buildings.
In construction surveying for this project, data acquisition is used to verify if as-built levee elevations match with flood design heights specified from hydrologic/hydraulic engineers. Construction quality assurance has been used to estimate quantity takeoffs including verification of excavation and removal of low-level site contaminants such as DDT (dichloro-diphenyl-trichloroethane) and PAH (polycyclic aromatic hydrocarbon), calculate excavation and fill volumes, or even isolate UXO (unexploded ordinance) areas for safety.
Mapping Is Important
The project base map is a very important component of the Hamilton Wetland Restoration Project. As an update to the 1997 base map, an aerial survey was conducted to provide up-to-date survey information and high-resolution imagery to develop a DTM and a topographic feature map. Furthermore, this data was used to update the map using newer horizontal and vertical datums, principally converting to NAD1983 and NAVD1988 in the California state plane projection. The project deliverables included color digital orthos in Tiff format containing 0.4-foot ground sample distance (pixel size) and a composite photo in MrSid format.
A series of controls were set up for the flight path network for the project. At the request of the project delivery team, the National Geodetic Survey (NGS) reviewed the numerous survey control installations. Many of the controls set onsite were incorporated into the NGS's database for GPS survey datasheets.
Construction activity after each construction season reflected outdated areas on the basemap. After understanding the potential impacts and delays of using obsolete data to planning, design, and construction, the project delivery team deemed it necessary to expend resources to keep it current. However, updating these areas was challenging because it involved making sure the replaced survey data integrated correctly into the existing DTM network. The updated points were primarily acquired from sub-centimeter RTK GPS or other traditional survey methods performed by survey consultants and the Corps of Engineers in-house survey crew. The Corps of Engineers GIS section served as the lead in the periodic survey updates on the basemap using a combination of CAD or GIS-related software.
Surveying also played a role in geotechnical instrumentation. A series of geotechnical studies conducted by URS and Arup, two large engineering firms, evaluated the subsurface conditions through field and laboratory data. One of the deliverables was to evaluate any ground movement induced on the neighboring residential and commercial properties using specialized geotechnical instruments and survey markers. Surveyed instruments in the form of settlement plates and settlement markers used to evaluate the foundation consolidation were installed on all the perimeter levees and the experimental Test Fill. Survey data collected from the Test Fill was used to calibrate soil deformation predictions from wetland and levee effects.
The overall monitoring program was used to validate that the geotechnical models are within specified threshold limits and to evaluate foundation consolidation for staged levee construction. Specialized survey instruments called pipe displacement markers (PDM), designed by the Corps of Engineers, were used to monitor and evaluate movement of a 52-inch outfall pipeline about 30 feet from the levee outboard toe. This pipeline is owned and operated by the Novato Sanitary District and functions several months a year to discharge treated effluent into the San Pablo Bay. The pipeline parallels the two levee systems for approximately three miles with PDMs installed at approximately 200-foot increments. The intent of the monitoring program is to collect soil deformation movement caused from the levee construction and to modify construction activities accordingly to mitigate further movement. Because the predicted movement is relatively small, high survey accuracy is required. The resulting survey data collected is reviewed under the direction of a California registered professional land surveyor.
In addition to monitoring the aforementioned existing geotechnical instruments on the perimeter levees, the Hamilton project delivery team has taken extra precaution in verifying ground subsurface predictions on structures outside the project limits. Adhesive reflective targets installed on selected residential home windows are surveyed at predetermined dates. Additionally, selected ground monuments are also surveyed and monitored for movement between the homes and the project. This monitoring program will end in 2010.
However, long-term monitoring will not end upon the groundbreaking of dredge import for wetland construction. The wetlands and associated features will be surveyed and monitored long after the project is completed to verify that features have met design intent developed during the planning phases. The collected survey data will determine settlement and habitat elevations, which directly impact plant and wildlife survival. For example, the northern seasonal wetland is designed to protect small wildlife from predators by creating islands during high tide and provide land bridging during low tides.
Challenges in the Mud
Bordered by San Pablo Bay, the Hamilton Airfield is characterized primarily by soft marine clays known as bay mud. This varies in thickness between 40 to 70 feet across the site, creating a so-called "bowl of Jell-O." The western project perimeter contains adjacent residential and commercial buildings. Similarly, soft marine clays underlie the northern and eastern project perimeter.
Establishing permanent survey controls on the project for high-accuracy monitoring would require installing through the soft bay mud into stiff alluvium, which can range to 70 feet in depth. This was considered an option because the existing permanent controls were located outside the project site and would require considerable traversing using traditional survey methods. However, these were found to be costly to install. Team members and consultants considered the various heavy construction and future planned activities that may damage or dislocate the permanent project control. The project delivery team determined that a permanent project control onsite was not needed now because of future project uncertainties but would be reconsidered later.
Monitoring a 52-inch-diameter outfall pipe paralleling constructed levees and other project features over soft soil proves challenging. Understanding the survey requirements is important to prevent construction-related effects leading to leakage or rupturing in the pipeline. This translates to high accuracy and repeatability challenges when horizontal monuments and vertical benchmarks are often not near the monitoring area. Thus, calibrated survey instruments with high precision and accuracy and experienced land surveyors familiar with working in soft subsurface conditions are important in obtaining quality data.
The baseline surveys are the most important aspect of the monitoring program for the project, which incorporated several datums. The vertical datums were NGVD (National Geodetic Vertical Datum) 1929, the NAVD (North American Vertical Datum) 1988, and the tidal datums. Although they appear as only a simple conversion, the common misuse and/or confusion could potentially cause major problems. Datums can vary by several feet, which could potentially cause flood overtopping of a levee, a component of levee failure. This could translate to schedule delays and higher project costs if caught late in the project. To avoid confusion between vertical datums, Bill Firth, PE, a technical specialist in hydraulic engineering for the U.S. Army Corps of Engineers, developed a simple conversion sheet between the vertical datums (tidal and land).
Early data collected for this project prior to 2000 have horizontal coordinates in NAD1927 and a vertical datum in NGVD 1929 in U.S. survey foot. Newer acquired land survey data are horizontally in NAD1983 and vertically in NAVD1988 in U.S. survey foot. All older land-based datums and tidal datums are converted to meet the aforementioned datum to avoid confusion and detrimental effects.
GIS Enters the Picture
The Hamilton Wetland Restoration Project contains a wealth of data, and if properly managed, it can serve as a valuable resource. The team has incorporated its collected field, design, and survey data into its long-term data management program, interfacing this with ESRI's ArcGIS software. An abundance of field, laboratory, and survey data compiled from geotechnical studies and field exploration exists. The Corps plans to integrate software such as Gint, database software that stores and outputs engineering diagrams for its subsurface data compatible with ArcGIS. Such examples are part of the Corps of Engineers' adaptive management plan to effectively store, organize, and visualize collected data on a GIS.
Mapping-grade GPS equipment has been used to delineate borrow and excavation limits or boring locations for this project. Corps of Engineers field technicians use the Trimble Geo-XH or Geo-XT, with differential post processing at the sub-foot or sub-meter accuracy. Other managed data include photos taken with a GPS-fitted camera and annotated with GPS coordinates, notes, and orientation. Ricoh and Geospatial Experts manufacture the camera and software, respectively. Processed photos can be overlain on a web-based image/ USGS quadrangle map, exported as an ESRI shapefile, or viewed on Google Earth. This allows the Corps of Engineers to organize their photo inventory on a georeferenced map or GIS rather than storing the photos on a desktop folder with little or no descriptions as to where they are geographically. In addition, this allows for an easy display of information in a format that is understandable to other project members or managers that may be unfamiliar with the project site.
The Corps of Engineers in San Francisco is currently purchasing the Leica 1200 series, a multi-function total station and GPS. Because the restoration site is located in an area primarily with open sky, GPS is ideal for sub-centimeter- level surveying for quality assurance. The project will rely on Leica's RTKmax network, a permanent control network that allows real time kinematic correction through the internet via integrated cell phone transmission.
This is just one the many surveying technologies that will come into play as the U.S. Army Corps of Engineers and others undertake this massive project to return a closed military base to its former glory as a wetland.
About the Authors
Chris Wang, PE, CMS is a civil engineer and mapping scientist in the geo-sciences section of the U.S. Army Corps of Engineers in San Francisco. He received his M.S. in Geotechnical Engineering from the U. of California, Berkeley. He is responsible for implementation of the field GPS and survey equipment and provides geotechnical support to the Hamilton Wetland Restoration Project.
Edgar V. Salire, PE, BCEE is a civil engineer and a board-certified environmental engineer in the geo-sciences section of the U.S. Army Corps of Engineers in San Francisco. He received his Master of Engineering in Geotechnical Engineering from Arizona State U. He is the lead geotechnical engineer for the Hamilton Wetland Restoration Project.
Feature: At the Forefront of Wetland Restoration
Chris Wang and Edgar Salire
Most people know that wetlands are steadily declining nationwide and that we are losing their numerous biological, ecological, environmental, and recreational benefits. California alone has seen a drastic decline caused by human-related activities. Only recently has government policy change halted further destruction of wetlands. As a prime example, several governmental agencies led by the U.S. Army Corps of Engineers, the California Coastal Conservancy, and the San Francisco Bay Conservation and Development Commission are undertaking wetland restoration on the former Hamilton Army Airfield.
The Hamilton Wetlands Restoration Project is located in the city of Novato, California, about 25 miles north of San Francisco. The former airfield was active until the early 1970s, and then in the 1990s it was closed as part of the Base Realignment and Closure Program. The area was originally a natural wetland but was diked off from San Francisco Bay waters in the late 1800s. Today, the project footprint covers 988 acres of wetlands, home to several protected species such as the clapper rail, salt harvest mouse, and the burrowing owl. The cost to restore the historical wetlands will exceed several hundred million dollars.
This project is multifaceted in that it will not only create a wetland but also recycle dredge spoils from the Port of Oakland harbor-deepening project, which is normally disposed of in a landfill or an offshore site. The dredge materials will be enclosed by a series of constructed perimeter levees, thereby creating a "bathtub" effect. Once the dredge material is imported, it will be sculpted to create a northern seasonal wetland and a southern tidal wetland. Survey instruments installed at predetermined intervals will guide the bulldozers as they sculpt the site to design elevations.
Surveying is incorporated in the design, construction, and monitoring phases of the Hamilton Wetland Restoration Project. The data collected are incorporated in civil design, hydrologic/ hydraulic design, and geotechnical engineering to document prior, existing, and future conditions. Surveying tells the story of the wetland restoration process by documenting many construction activities ongoing at any given time.
The Hamilton survey team and survey consultants have deployed a multitude of surveying technology in the forms of RTK GPS and traditional surveying. To optimize effectiveness, survey crews and remote sensing technology were deployed to complete construction activities. High-resolution orthophoto imagery was developed and used to produce a project basemap. Derived from the rectified imagery and composed of a feature map and a digital terrain model (DTM), this is a key component in making project design decisions.
Hydrologically, survey data forms a direct input into the design and has proved instrumental in developing a self-sustaining wetland design, thereby preventing short-circuiting of design water flow between the southern seasonal and northern tidal wetland. Survey contributions to geotechnical engineering have come in the form of monitoring of ground response and impact on existing infrastructures such as pipelines and residential and commercial buildings.
In construction surveying for this project, data acquisition is used to verify if as-built levee elevations match with flood design heights specified from hydrologic/hydraulic engineers. Construction quality assurance has been used to estimate quantity takeoffs including verification of excavation and removal of low-level site contaminants such as DDT (dichloro-diphenyl-trichloroethane) and PAH (polycyclic aromatic hydrocarbon), calculate excavation and fill volumes, or even isolate UXO (unexploded ordinance) areas for safety.
Mapping Is Important
The project base map is a very important component of the Hamilton Wetland Restoration Project. As an update to the 1997 base map, an aerial survey was conducted to provide up-to-date survey information and high-resolution imagery to develop a DTM and a topographic feature map. Furthermore, this data was used to update the map using newer horizontal and vertical datums, principally converting to NAD1983 and NAVD1988 in the California state plane projection. The project deliverables included color digital orthos in Tiff format containing 0.4-foot ground sample distance (pixel size) and a composite photo in MrSid format.
A series of controls were set up for the flight path network for the project. At the request of the project delivery team, the National Geodetic Survey (NGS) reviewed the numerous survey control installations. Many of the controls set onsite were incorporated into the NGS's database for GPS survey datasheets.
Construction activity after each construction season reflected outdated areas on the basemap. After understanding the potential impacts and delays of using obsolete data to planning, design, and construction, the project delivery team deemed it necessary to expend resources to keep it current. However, updating these areas was challenging because it involved making sure the replaced survey data integrated correctly into the existing DTM network. The updated points were primarily acquired from sub-centimeter RTK GPS or other traditional survey methods performed by survey consultants and the Corps of Engineers in-house survey crew. The Corps of Engineers GIS section served as the lead in the periodic survey updates on the basemap using a combination of CAD or GIS-related software.
Surveying also played a role in geotechnical instrumentation. A series of geotechnical studies conducted by URS and Arup, two large engineering firms, evaluated the subsurface conditions through field and laboratory data. One of the deliverables was to evaluate any ground movement induced on the neighboring residential and commercial properties using specialized geotechnical instruments and survey markers. Surveyed instruments in the form of settlement plates and settlement markers used to evaluate the foundation consolidation were installed on all the perimeter levees and the experimental Test Fill. Survey data collected from the Test Fill was used to calibrate soil deformation predictions from wetland and levee effects.
The overall monitoring program was used to validate that the geotechnical models are within specified threshold limits and to evaluate foundation consolidation for staged levee construction. Specialized survey instruments called pipe displacement markers (PDM), designed by the Corps of Engineers, were used to monitor and evaluate movement of a 52-inch outfall pipeline about 30 feet from the levee outboard toe. This pipeline is owned and operated by the Novato Sanitary District and functions several months a year to discharge treated effluent into the San Pablo Bay. The pipeline parallels the two levee systems for approximately three miles with PDMs installed at approximately 200-foot increments. The intent of the monitoring program is to collect soil deformation movement caused from the levee construction and to modify construction activities accordingly to mitigate further movement. Because the predicted movement is relatively small, high survey accuracy is required. The resulting survey data collected is reviewed under the direction of a California registered professional land surveyor.
In addition to monitoring the aforementioned existing geotechnical instruments on the perimeter levees, the Hamilton project delivery team has taken extra precaution in verifying ground subsurface predictions on structures outside the project limits. Adhesive reflective targets installed on selected residential home windows are surveyed at predetermined dates. Additionally, selected ground monuments are also surveyed and monitored for movement between the homes and the project. This monitoring program will end in 2010.
However, long-term monitoring will not end upon the groundbreaking of dredge import for wetland construction. The wetlands and associated features will be surveyed and monitored long after the project is completed to verify that features have met design intent developed during the planning phases. The collected survey data will determine settlement and habitat elevations, which directly impact plant and wildlife survival. For example, the northern seasonal wetland is designed to protect small wildlife from predators by creating islands during high tide and provide land bridging during low tides.
Challenges in the Mud
Bordered by San Pablo Bay, the Hamilton Airfield is characterized primarily by soft marine clays known as bay mud. This varies in thickness between 40 to 70 feet across the site, creating a so-called "bowl of Jell-O." The western project perimeter contains adjacent residential and commercial buildings. Similarly, soft marine clays underlie the northern and eastern project perimeter.
Establishing permanent survey controls on the project for high-accuracy monitoring would require installing through the soft bay mud into stiff alluvium, which can range to 70 feet in depth. This was considered an option because the existing permanent controls were located outside the project site and would require considerable traversing using traditional survey methods. However, these were found to be costly to install. Team members and consultants considered the various heavy construction and future planned activities that may damage or dislocate the permanent project control. The project delivery team determined that a permanent project control onsite was not needed now because of future project uncertainties but would be reconsidered later.
Monitoring a 52-inch-diameter outfall pipe paralleling constructed levees and other project features over soft soil proves challenging. Understanding the survey requirements is important to prevent construction-related effects leading to leakage or rupturing in the pipeline. This translates to high accuracy and repeatability challenges when horizontal monuments and vertical benchmarks are often not near the monitoring area. Thus, calibrated survey instruments with high precision and accuracy and experienced land surveyors familiar with working in soft subsurface conditions are important in obtaining quality data.
The baseline surveys are the most important aspect of the monitoring program for the project, which incorporated several datums. The vertical datums were NGVD (National Geodetic Vertical Datum) 1929, the NAVD (North American Vertical Datum) 1988, and the tidal datums. Although they appear as only a simple conversion, the common misuse and/or confusion could potentially cause major problems. Datums can vary by several feet, which could potentially cause flood overtopping of a levee, a component of levee failure. This could translate to schedule delays and higher project costs if caught late in the project. To avoid confusion between vertical datums, Bill Firth, PE, a technical specialist in hydraulic engineering for the U.S. Army Corps of Engineers, developed a simple conversion sheet between the vertical datums (tidal and land).
Early data collected for this project prior to 2000 have horizontal coordinates in NAD1927 and a vertical datum in NGVD 1929 in U.S. survey foot. Newer acquired land survey data are horizontally in NAD1983 and vertically in NAVD1988 in U.S. survey foot. All older land-based datums and tidal datums are converted to meet the aforementioned datum to avoid confusion and detrimental effects.
GIS Enters the Picture
The Hamilton Wetland Restoration Project contains a wealth of data, and if properly managed, it can serve as a valuable resource. The team has incorporated its collected field, design, and survey data into its long-term data management program, interfacing this with ESRI's ArcGIS software. An abundance of field, laboratory, and survey data compiled from geotechnical studies and field exploration exists. The Corps plans to integrate software such as Gint, database software that stores and outputs engineering diagrams for its subsurface data compatible with ArcGIS. Such examples are part of the Corps of Engineers' adaptive management plan to effectively store, organize, and visualize collected data on a GIS.
Mapping-grade GPS equipment has been used to delineate borrow and excavation limits or boring locations for this project. Corps of Engineers field technicians use the Trimble Geo-XH or Geo-XT, with differential post processing at the sub-foot or sub-meter accuracy. Other managed data include photos taken with a GPS-fitted camera and annotated with GPS coordinates, notes, and orientation. Ricoh and Geospatial Experts manufacture the camera and software, respectively. Processed photos can be overlain on a web-based image/ USGS quadrangle map, exported as an ESRI shapefile, or viewed on Google Earth. This allows the Corps of Engineers to organize their photo inventory on a georeferenced map or GIS rather than storing the photos on a desktop folder with little or no descriptions as to where they are geographically. In addition, this allows for an easy display of information in a format that is understandable to other project members or managers that may be unfamiliar with the project site.
The Corps of Engineers in San Francisco is currently purchasing the Leica 1200 series, a multi-function total station and GPS. Because the restoration site is located in an area primarily with open sky, GPS is ideal for sub-centimeter- level surveying for quality assurance. The project will rely on Leica's RTKmax network, a permanent control network that allows real time kinematic correction through the internet via integrated cell phone transmission.
This is just one the many surveying technologies that will come into play as the U.S. Army Corps of Engineers and others undertake this massive project to return a closed military base to its former glory as a wetland.
About the Authors
Chris Wang, PE, CMS is a civil engineer and mapping scientist in the geo-sciences section of the U.S. Army Corps of Engineers in San Francisco. He received his M.S. in Geotechnical Engineering from the U. of California, Berkeley. He is responsible for implementation of the field GPS and survey equipment and provides geotechnical support to the Hamilton Wetland Restoration Project.
Edgar V. Salire, PE, BCEE is a civil engineer and a board-certified environmental engineer in the geo-sciences section of the U.S. Army Corps of Engineers in San Francisco. He received his Master of Engineering in Geotechnical Engineering from Arizona State U. He is the lead geotechnical engineer for the Hamilton Wetland Restoration Project.
lidar benefits
Professional Surveyor April 2008 Volume 28 Number 4
Feature: Lidar Fact and Fiction
Todd Stennett and Sandra Wade-Grusky
While it may seem new, lidar (light detection and ranging) has actually been around for over 30 years now. The technology works similarly to radar (radio detection and ranging), but transmits and receives light from lasers rather than radio waves from radio signals. Its use goes all the way back to the 1970s with the introduction of systems by NASA. But through the 1970s and 80s and the first half of the 90s, the technology was far too cumbersome and temperamental to be deployed commercially. Its integrators worked hard to reduce weight and size, increase accuracy, and increase reliability.
The process took decades, but by the late 1990s, we saw the first commercial sensors deployed. The technology, as well as computing power that increases lidar speed and accuracy, has progressed to make lidar a preferred alternative for developing digital elevation models (DEM) of the Earth's surface.
Today, about 150 sensors are installed in aircraft throughout the world, with about half of these active in the private sector. The rest are retired or used by governments or educational institutions. As owners and operators of four of these sensors, we frequently come across a few myths about lidar. Let's take a look at a few that impact professional surveyors.
Myth #1: Lidar activity is not classified as land surveying and therefore is not governed and regulated accordingly
Well, the industry frequently operates under that assumption, but it's dangerous to do so. It varies by state and specific activity. To get to the truth, we sent certified letters to every state board of registrars. As expected, some simply cited the applicable references and code numbers, sidestepping a direct response. Proudly, some 22 states stepped up and rendered their positions on the matter.
We asked each state a series of questions on this topic. Did you know that in one or more states:
The act of collecting lidar data is deemed to be regulated under state licensure law, including the operation of a lidar sensor.
The act of computation of collected lidar data is deemed to be regulated under state licensure law.
The act of occupying geodetic control points with GPS receivers (to position the aircraft) is deemed to be regulated under state licensure law.
The act of measuring ground elevations with GPS receivers (used internally by a firm to check their lidar measurements) is deemed to be regulated under state licensure law.
The states vary widely on their experience and education requirements for Professional or Registered Land Surveyor licensure. And some states do not consider ANY of the above items to require a license.
I think we'd all agree that at some point in the process, coordinates are computed, and that those coordinates may be used for a variety of purposes. Many of these purposes are governed by licensure laws, and generally for good reason.
In general, it's wise to ensure coordination and legitimate oversight with a PLS on all lidar projects, and we find that local knowledge is usually efficient. (If you're experienced with or interested in lidar quality control, we're always interested to have more friends across the nation and world. Give us a shout, and express your interest.)
Myth #2: Lidar is cost prohibitive on most small projects
The minimum breakeven scope of work for some lidar firms is 20 to 40 acres of typical terrain, smaller if vegetation or access becomes an issue. While many firms don't wish to perform projects smaller than 25 to 50 square kilometers, others routinely perform high volumes of small sites. When performing on behalf of licensed professionals who get involved in the survey's groundwork, we price any state in the Southwest at about $3,500 plus $1.49 per acre, if you can provide lead time. Once the acreage reaches a few hundred, that per-acre fee can fall—a long way. The marginal cost to collect one more acre, for most sensors out there, is less than 10 cents. Our price for these marginal acres has gone as low as $0.15 per acre when we get into the largest projects, typically greater than 1,000 square miles. The above pricing applies to data in support of 2-foot contouring to ASPRS Class 1 standards. It covers mass points, cleaned to bald earth, along with the "removed features" file, which contains all the structures, vegetation, birds, aircraft, and other non-ground features we pick up while flying.
The trick is to take advantage of that low marginal cost and pool a few nearby projects, even with competitors that are cooperative. Also, national road shows are offered where firms fly predetermined areas around the country and sign up customers. With this, firms can take advantage of lidar for smaller sites anywhere in the United States and avoid having to meet a $25,000 or higher minimum project size. It just takes a bit of searching on your favorite search engine and gathering a few references.
Myth #3: Lidar can't support one-foot contouring
Yes, lidar can support 1-foot contouring, even to the most rigorous standards, but it may not be cost effective to deploy it for this purpose in certain conditions. We've run more photogrammetry firms through their own assessments than I can count, and the results are consistent. First, disbelief. Then, testing and approval at 2-foot interval mapping. Then, tighter flight constraints (especially with regard to GPS, where the majority of error is introduced) and testing at 1-foot intervals. Lidar is far better for these applications in some terrain and vegetation types and far better for pure volumetric projects such as landfills, earthmoving, etc.
On the other hand, lidar should NOT be used to support final, large, design-scale mapping of highly intricate terrain and features where breaklines and planimetrics are the vital component, unless you have a skilled team for the photogrammetric editing processes. While lidar will clearly show the crown of roadways and cul-de-sacs, it won't deliver a perfect face-of-curb. It is, after all, discrete point data and not continuous line data.
Some lidar providers are claiming accuracies up to 7 and 8 centimeters at 2-sigma. We believe it can be achieved, but typically promise only to 15 centimeters at this confidence interval, because that's easily repeatable.
Myth #4: Lidar can see through trees
Well, that would be cool, for sure. Unfortunately, it's only true in one sense. If you walk into an area of dense canopy and take a look at the ground, you can see that a certain percentage of the ground is hit by direct sunlight. That percentage very closely correlates to the percentage of your laser shots that will make it to ground. If you have 80 percent shadow on ground, then about one in five shots will make it to ground. With repetition rates now above 150,000 shots per second, a dense array of lidar points isn't difficult. We're shooting dozens of areas right now at around 10 shots per square meter, and sometimes triple that for our helicopter work. But the percentage opening in canopy is the percentage of these shots that will provide a reliable ground surface.
We've been called to survey a farmer's land to help eliminate his gopher dens in one case and to help locate buried treasure in another. Not with lidar. We've been called to locate, rescue, and recover people who've fallen into icy waters. Not with lidar. But for most terrain needs between 1-foot and 1-meter vertical accuracies, lidar is a more cost-effective choice. That's why the industry's largest photogrammetry firms have all jumped on board. Because they don't want competitors to offer a more cost-effective solution to their own clients, many firms have decided to get in the game, whether they choose to outsource or bring the capabilities in-house.
Think You Can't Afford Lidar? Guess Again
To surveyors who haven't yet used the technology, lidar sounds like some futuristic Star Trek invention that costs a fortune to use. While lidar does represent the cutting edge of mapping techniques, the average aerial lidar project actually doesn't cost more than one completed with traditional photogrammetric methods. In the surveying community, however, the benefits of lidar over traditional aerial photogrammetry, including cost, are not well understood.
The basic components of a lidar airborne laser mapping system include a laser scanner and cooling system, GPS receivers, and an inertial navigation system (INS). The laser scanner mounts within a properly outfitted aircraft and emits infrared laser beams at a high frequency. The scanner records the difference in time between the emission of the laser pulses and the reception of the reflected signal. A mirror mounted in front of the laser rotates and causes the laser pulses to sweep at an angle, back and forth along a line. The position and orientation of the aircraft is determined using phase-differenced kinematic GPS. GPS systems are located in the aircraft and at several ground stations within the area to be mapped. The orientation of the aircraft is then controlled and determined by the INS.
The round trip travel time of the laser pulses from the aircraft to the ground are measured and recorded, along with the position and orientation of the aircraft at the time of transmission of each pulse. After the flight, the vectors from the aircraft to the ground are combined with the aircraft position at the time of each measurement, and the 3D XYZ coordinates of each ground point are computed.
The system can be operated at various scan frequencies and altitudes, depending on the measurement accuracy dictated by project requirements and the regulated eye-safe range of the laser. By accurately timing the round trip travel time of the light pulses to the surface, it is possible to determine the distance from the laser to the ground, typically with a precision of 10 to 25 centimeters. Typical operating specifications permit flying speeds of 50 to 200 knots, flying heights of 100 to 5,000 meters, scanning angles up to plus 20 degrees, and pulse rates of 2,000 to more than 100,000 pulses per second. These parameters yield enough data points to create a highly accurate digital terrain model (DTM). Typical users of this technology have achieved accuracies of roughly 15 centimeters at up to 95 percent confidence interval vertically and 1 foot or 30 centimeters horizontally.
Post-flight processing combines precise aircraft trajectories developed from differential GPS solutions with the corrected laser ranging data and aircraft roll, pitch, and heading information. Integration of this data produces a precise horizontal position and vertical elevation for each laser pulse. Each data point can be identified by type, i.e. ground, vegetation, building, power line, or other object. Once classified, it is simple to manipulate data, remove layers of data points, and create DTMs.
Today, the entire process of airborne laser mapping is highly automated from flight planning to data acquisition to the generation of digital terrain models. Airborne laser mapping instruments are active sensor systems, as opposed to passive imagery such as cameras. Consequently, they offer unique capabilities and benefits compared to traditional photogrammetry.
The absolute accuracy of the elevation data is 15 centimeters; relative accuracy can be less than 5 cm. Absolute accuracy of the XY data is dependent on operating parameters such as flight altitude, but accuracy in the range of tens of centimeters to one meter can usually be achieved.
The elevation data is generated at thousands of points per second, resulting in elevation point densities far greater than traditional ground survey methods. One hour of data collection can result in over 10,000,000 individually geo-referenced elevation points. With these high sampling rates, it is possible to rapidly complete a large topographic survey and still generate DTMs with a grid spacing of one meter or less.
But accuracy is not the only benefit of airborne laser mapping. The technology allows for extremely rapid rates of topographic data collection, resulting in exceptionally fast data delivery.
As the old commercials used to ask, "Now how much would you pay?"
But wait … lidar outperforms traditional photogrammetry in these other areas:
Lidar sensors can be operated in any weather and at low sun angles that would prevent an aerial photography survey.
Rural and remote areas can be surveyed easily and quickly because each XYZ point is individually geo-referenced, and aerial triangulation or orthorectification of data is not required.
Photogrammetric methods for DTM generation are very time consuming and labor intensive compared to airborne laser mapping.
While satisfactory results in zones with limited contrast, such as coasts, beaches, and wetlands, are difficult to achieve with traditional photogrammetry, lidar genare traditional generally gives good results in these areas.
Lidar performs well in forest areas where vegetation cover prevents visibility of the ground in aerial photographs.
Lidar is better for road, pipeline, or power line planning for narrow corridor mapping.
Lidar works well for open-pit mining operations where the final data is needed within a few hours of collection.
You might think that the myriad benefits of lidar would make it much more expensive, but studies have shown that lidar requires only 25 to 33 percent of the budget needed for photogrammetric compilation (see Petzold et al., 1999), possibly due to project delays caused by less-than-ideal environmental conditions or by the time-consuming, expensive processes required by traditional photogrammetry. With all the benefits and cost savings, the serious surveyor can't afford to not use aerial lidar.
About the Authors
Todd Stennett is the founder and CEO of Airborne 1 Corporation, based in El Segundo, California. The firm offers turnkey service, training for data and sensor operations, sensor rentals, and fractional sales of lidar assets.
Sandra Wade-Grusky, marketing manager for Airborne 1, is responsible for all internet and print marketing activities for the company.
Feature: Lidar Fact and Fiction
Todd Stennett and Sandra Wade-Grusky
While it may seem new, lidar (light detection and ranging) has actually been around for over 30 years now. The technology works similarly to radar (radio detection and ranging), but transmits and receives light from lasers rather than radio waves from radio signals. Its use goes all the way back to the 1970s with the introduction of systems by NASA. But through the 1970s and 80s and the first half of the 90s, the technology was far too cumbersome and temperamental to be deployed commercially. Its integrators worked hard to reduce weight and size, increase accuracy, and increase reliability.
The process took decades, but by the late 1990s, we saw the first commercial sensors deployed. The technology, as well as computing power that increases lidar speed and accuracy, has progressed to make lidar a preferred alternative for developing digital elevation models (DEM) of the Earth's surface.
Today, about 150 sensors are installed in aircraft throughout the world, with about half of these active in the private sector. The rest are retired or used by governments or educational institutions. As owners and operators of four of these sensors, we frequently come across a few myths about lidar. Let's take a look at a few that impact professional surveyors.
Myth #1: Lidar activity is not classified as land surveying and therefore is not governed and regulated accordingly
Well, the industry frequently operates under that assumption, but it's dangerous to do so. It varies by state and specific activity. To get to the truth, we sent certified letters to every state board of registrars. As expected, some simply cited the applicable references and code numbers, sidestepping a direct response. Proudly, some 22 states stepped up and rendered their positions on the matter.
We asked each state a series of questions on this topic. Did you know that in one or more states:
The act of collecting lidar data is deemed to be regulated under state licensure law, including the operation of a lidar sensor.
The act of computation of collected lidar data is deemed to be regulated under state licensure law.
The act of occupying geodetic control points with GPS receivers (to position the aircraft) is deemed to be regulated under state licensure law.
The act of measuring ground elevations with GPS receivers (used internally by a firm to check their lidar measurements) is deemed to be regulated under state licensure law.
The states vary widely on their experience and education requirements for Professional or Registered Land Surveyor licensure. And some states do not consider ANY of the above items to require a license.
I think we'd all agree that at some point in the process, coordinates are computed, and that those coordinates may be used for a variety of purposes. Many of these purposes are governed by licensure laws, and generally for good reason.
In general, it's wise to ensure coordination and legitimate oversight with a PLS on all lidar projects, and we find that local knowledge is usually efficient. (If you're experienced with or interested in lidar quality control, we're always interested to have more friends across the nation and world. Give us a shout, and express your interest.)
Myth #2: Lidar is cost prohibitive on most small projects
The minimum breakeven scope of work for some lidar firms is 20 to 40 acres of typical terrain, smaller if vegetation or access becomes an issue. While many firms don't wish to perform projects smaller than 25 to 50 square kilometers, others routinely perform high volumes of small sites. When performing on behalf of licensed professionals who get involved in the survey's groundwork, we price any state in the Southwest at about $3,500 plus $1.49 per acre, if you can provide lead time. Once the acreage reaches a few hundred, that per-acre fee can fall—a long way. The marginal cost to collect one more acre, for most sensors out there, is less than 10 cents. Our price for these marginal acres has gone as low as $0.15 per acre when we get into the largest projects, typically greater than 1,000 square miles. The above pricing applies to data in support of 2-foot contouring to ASPRS Class 1 standards. It covers mass points, cleaned to bald earth, along with the "removed features" file, which contains all the structures, vegetation, birds, aircraft, and other non-ground features we pick up while flying.
The trick is to take advantage of that low marginal cost and pool a few nearby projects, even with competitors that are cooperative. Also, national road shows are offered where firms fly predetermined areas around the country and sign up customers. With this, firms can take advantage of lidar for smaller sites anywhere in the United States and avoid having to meet a $25,000 or higher minimum project size. It just takes a bit of searching on your favorite search engine and gathering a few references.
Myth #3: Lidar can't support one-foot contouring
Yes, lidar can support 1-foot contouring, even to the most rigorous standards, but it may not be cost effective to deploy it for this purpose in certain conditions. We've run more photogrammetry firms through their own assessments than I can count, and the results are consistent. First, disbelief. Then, testing and approval at 2-foot interval mapping. Then, tighter flight constraints (especially with regard to GPS, where the majority of error is introduced) and testing at 1-foot intervals. Lidar is far better for these applications in some terrain and vegetation types and far better for pure volumetric projects such as landfills, earthmoving, etc.
On the other hand, lidar should NOT be used to support final, large, design-scale mapping of highly intricate terrain and features where breaklines and planimetrics are the vital component, unless you have a skilled team for the photogrammetric editing processes. While lidar will clearly show the crown of roadways and cul-de-sacs, it won't deliver a perfect face-of-curb. It is, after all, discrete point data and not continuous line data.
Some lidar providers are claiming accuracies up to 7 and 8 centimeters at 2-sigma. We believe it can be achieved, but typically promise only to 15 centimeters at this confidence interval, because that's easily repeatable.
Myth #4: Lidar can see through trees
Well, that would be cool, for sure. Unfortunately, it's only true in one sense. If you walk into an area of dense canopy and take a look at the ground, you can see that a certain percentage of the ground is hit by direct sunlight. That percentage very closely correlates to the percentage of your laser shots that will make it to ground. If you have 80 percent shadow on ground, then about one in five shots will make it to ground. With repetition rates now above 150,000 shots per second, a dense array of lidar points isn't difficult. We're shooting dozens of areas right now at around 10 shots per square meter, and sometimes triple that for our helicopter work. But the percentage opening in canopy is the percentage of these shots that will provide a reliable ground surface.
We've been called to survey a farmer's land to help eliminate his gopher dens in one case and to help locate buried treasure in another. Not with lidar. We've been called to locate, rescue, and recover people who've fallen into icy waters. Not with lidar. But for most terrain needs between 1-foot and 1-meter vertical accuracies, lidar is a more cost-effective choice. That's why the industry's largest photogrammetry firms have all jumped on board. Because they don't want competitors to offer a more cost-effective solution to their own clients, many firms have decided to get in the game, whether they choose to outsource or bring the capabilities in-house.
Think You Can't Afford Lidar? Guess Again
To surveyors who haven't yet used the technology, lidar sounds like some futuristic Star Trek invention that costs a fortune to use. While lidar does represent the cutting edge of mapping techniques, the average aerial lidar project actually doesn't cost more than one completed with traditional photogrammetric methods. In the surveying community, however, the benefits of lidar over traditional aerial photogrammetry, including cost, are not well understood.
The basic components of a lidar airborne laser mapping system include a laser scanner and cooling system, GPS receivers, and an inertial navigation system (INS). The laser scanner mounts within a properly outfitted aircraft and emits infrared laser beams at a high frequency. The scanner records the difference in time between the emission of the laser pulses and the reception of the reflected signal. A mirror mounted in front of the laser rotates and causes the laser pulses to sweep at an angle, back and forth along a line. The position and orientation of the aircraft is determined using phase-differenced kinematic GPS. GPS systems are located in the aircraft and at several ground stations within the area to be mapped. The orientation of the aircraft is then controlled and determined by the INS.
The round trip travel time of the laser pulses from the aircraft to the ground are measured and recorded, along with the position and orientation of the aircraft at the time of transmission of each pulse. After the flight, the vectors from the aircraft to the ground are combined with the aircraft position at the time of each measurement, and the 3D XYZ coordinates of each ground point are computed.
The system can be operated at various scan frequencies and altitudes, depending on the measurement accuracy dictated by project requirements and the regulated eye-safe range of the laser. By accurately timing the round trip travel time of the light pulses to the surface, it is possible to determine the distance from the laser to the ground, typically with a precision of 10 to 25 centimeters. Typical operating specifications permit flying speeds of 50 to 200 knots, flying heights of 100 to 5,000 meters, scanning angles up to plus 20 degrees, and pulse rates of 2,000 to more than 100,000 pulses per second. These parameters yield enough data points to create a highly accurate digital terrain model (DTM). Typical users of this technology have achieved accuracies of roughly 15 centimeters at up to 95 percent confidence interval vertically and 1 foot or 30 centimeters horizontally.
Post-flight processing combines precise aircraft trajectories developed from differential GPS solutions with the corrected laser ranging data and aircraft roll, pitch, and heading information. Integration of this data produces a precise horizontal position and vertical elevation for each laser pulse. Each data point can be identified by type, i.e. ground, vegetation, building, power line, or other object. Once classified, it is simple to manipulate data, remove layers of data points, and create DTMs.
Today, the entire process of airborne laser mapping is highly automated from flight planning to data acquisition to the generation of digital terrain models. Airborne laser mapping instruments are active sensor systems, as opposed to passive imagery such as cameras. Consequently, they offer unique capabilities and benefits compared to traditional photogrammetry.
The absolute accuracy of the elevation data is 15 centimeters; relative accuracy can be less than 5 cm. Absolute accuracy of the XY data is dependent on operating parameters such as flight altitude, but accuracy in the range of tens of centimeters to one meter can usually be achieved.
The elevation data is generated at thousands of points per second, resulting in elevation point densities far greater than traditional ground survey methods. One hour of data collection can result in over 10,000,000 individually geo-referenced elevation points. With these high sampling rates, it is possible to rapidly complete a large topographic survey and still generate DTMs with a grid spacing of one meter or less.
But accuracy is not the only benefit of airborne laser mapping. The technology allows for extremely rapid rates of topographic data collection, resulting in exceptionally fast data delivery.
As the old commercials used to ask, "Now how much would you pay?"
But wait … lidar outperforms traditional photogrammetry in these other areas:
Lidar sensors can be operated in any weather and at low sun angles that would prevent an aerial photography survey.
Rural and remote areas can be surveyed easily and quickly because each XYZ point is individually geo-referenced, and aerial triangulation or orthorectification of data is not required.
Photogrammetric methods for DTM generation are very time consuming and labor intensive compared to airborne laser mapping.
While satisfactory results in zones with limited contrast, such as coasts, beaches, and wetlands, are difficult to achieve with traditional photogrammetry, lidar genare traditional generally gives good results in these areas.
Lidar performs well in forest areas where vegetation cover prevents visibility of the ground in aerial photographs.
Lidar is better for road, pipeline, or power line planning for narrow corridor mapping.
Lidar works well for open-pit mining operations where the final data is needed within a few hours of collection.
You might think that the myriad benefits of lidar would make it much more expensive, but studies have shown that lidar requires only 25 to 33 percent of the budget needed for photogrammetric compilation (see Petzold et al., 1999), possibly due to project delays caused by less-than-ideal environmental conditions or by the time-consuming, expensive processes required by traditional photogrammetry. With all the benefits and cost savings, the serious surveyor can't afford to not use aerial lidar.
About the Authors
Todd Stennett is the founder and CEO of Airborne 1 Corporation, based in El Segundo, California. The firm offers turnkey service, training for data and sensor operations, sensor rentals, and fractional sales of lidar assets.
Sandra Wade-Grusky, marketing manager for Airborne 1, is responsible for all internet and print marketing activities for the company.
Corner Types:
Professional Surveyor April 2008 Volume 28 Number 4
Rules of the Game: Types of Corners
Donald A. Wilson, LLS, PLS, RPF
Since there sometimes seems to be some confusion as to what corners really are, perhaps further clarification is in order. The court system has provided considerable insight. In the previous article, a definition was presented. This article will focus on the different types of corners that might be encountered.
Care should be taken when discussing corners, as there are many types. There are property corners, but also street corners, building corners, and fence corners, which may or may not be property corners, depending upon the circumstances.
Classifications of Corners
A corner, according to the Tennessee court, may be defined as the intersection of two converging lines or surfaces; an angle, whether internal or external; as the "corner" of a building, the four "corners" of a square, the "corner" of two streets. A mere variation in a line does not constitute a "corner" (Christian v. Gernt, et al., 64 S.W. 399 [Tenn. Ch., 1900]). In this case, the court was quoting from the Century Dictionary. One of the parties insisted that a particular point was a corner, whereupon the court, relying on the above definition, stated that it cannot be a corner but is a mere variation in the line.
Closing corner: a corner at the intersection of a surveyed boundary with a previously established boundary line. In the survey of the public land of the United States, when a line connecting the last section corner and the objective corner on an established township boundary departs from the astronomic meridian by more than an allowable deviation, the line being surveyed is projected on cardinal to an intersection with the township boundary, where a closing corner is established and connection made to the previously established corner (quoted in Lugon v. Crosier, 240 P. 462, 78 Colo. 141 [1925]).
Existent corner: one whose position is identifiable by evidence of monument, its accessories, or description in field notes, or can be located by acceptable supplemental survey record, some physical evidence, or testimony (Manual of Instructions, Bureau of Land Management [1973], quoted in Reid v. Dunn, 20 Cal. Rptr. 273 [1962]). This was addressed in Hartshorn v. Wright, 11 F. 715 (N.J. C.C., 1813), wherein the court addressed an objection that a description was uncertain because the courses of a creek were too indefinite a boundary and that no plot of the land had been produced to show the beginning and course of the western line. The court replied that the language, "'to a spot from whence a south course will strike the beginning,' though not marked by any visible object, is susceptible of precise location by aid of the compass, as there could be but one spot on the margin of the creek, whence a due south course would strike the beginning."
Lost corner: a point of a survey whose position cannot be determined, beyond reasonable doubt, either from traces of the original marks or from acceptable evidence or testimony that bears upon the original position, and whose location can be restored only by reference to one or more interdependent corners (Manual of Instructions, Bureau of Land Management [1973], quoted in Reid v. Dunn, 20 Cal.Rptr. 273 [1962]; U.S. v. Doyle, 468 F.2d 633 [Colo., 1972], paraphrased in Fellows v. Willett, 98 Okla. 248 [1923]).
Meander corner: a corner marking the intersection of a township or section boundary and the mean high-water line of a body of water. Also a corner on a meander line. The Wisconsin court in Thunder Lake Lumber Co. v. Carpenter, 200 N.W. 302, 184 Wis. 580 stated in 1924 that a "meander corner" is not a fixed point for measurements, as are section and quarter corners, but is a marker for courses.
Nonexistent corner: one which has never existed, cannot be said to be lost, obliterated, or established under the rules relating to the establishment of lost or obliterated corners, but should be established at the place where the original surveyor should have put it (Lugon v. Crosier, 240 P. 462, 78 Colo. 141 [1925]). In this case, the court rejected the arguments as to how this corner should be replaced. It concluded that the corner in question is a closing corner, but not one from which a standard parallel has been initiated, nor to which one has been directed. Therefore, the rules do not relate to the question in this case.
If it did, "it cannot be said to be lost or obliterated. It never existed and so cannot, strictly speaking, be said to be lost or obliterated. If the monument were lost or obliterated there would be some reason to attempt to re-locate it, and perhaps the method prescribed in rule 47 is as good a way as any other, but when it is a myth, never on the ground, the natural, straightforward and sensible way is to establish the corner at the place where the original surveyor ought to have put it and that is where the north course of the east line of the section meets the correction line at right angles, and that is where the report puts it. Everybody knows that that is where the section line ought to have closed and where the original surveyor, honest or dishonest, meant to close it; that his duty required him to close it there, so that the enclosure of his lines might be a rectangle or nearly so. Why should courts be less reasonable than reasonable men?"
Obliterated corner: one at whose point there are no remaining traces of the monument or its accessories, but whose location has been perpetuated, or the point for which may be recovered beyond reasonable doubt by the acts and testimony of the interested landowners, competent surveyors, other qualified local authorities, or witnesses, or by some acceptable record evidence (Manual of Instructions, Bureau of Land Management [1973], quoted in Reid v. Dunn, 20 Cal.Rptr. 273 [1962]; U.S. v. Doyle, 468 F.2d 633 [Colo., 1972], paraphrased in Fellows v. Willett, 98 Okla. 248 [1923]).
A property corner is a corner of a parcel of land, right, or interest, which is created by title documents or some mechanism of title creation. It is the point where two property lines intersect.
Quarter corner: a corner of a Quarter Section of land. As distinguished from a section corner, in the government surveys, it means the corner on the section line midway between the section corners (Rud v. Board of County Commissioners of Pope County, 66 Minn. 358 [1896]).
Section corner: a corner of a section of land, or a corner at an extremity of a section line.
Sixteenth corner: a corner of a sixteenth section of land or a quarter-quarter section. It may also be defined as a corner at an extremity of a boundary of a quarter-quarter section, or midpoint between the controlling corners on a section or township boundary.
Standard corner: one that is on a standard parallel or base line.
Township corner: a corner at the extremity of a township boundary or the corner of a township.
Witness corner: by conventional usage, a monumented point usually on a line of the survey and near a corner. It is employed in situations where it is impracticable (or impossible) to occupy the site of a corner. A witness point is a monumented station on a line of a survey and is used to perpetuate an important location more or less remote from and without special relation to any regular corner (Manual of Instructions, Bureau of Land Management [1973]).
Corner accessory: a physical object adjacent to a corner to which the corner is referred for future identification or restoration. Accessories include bearing trees, mounds, pits, ledges, rocks, and other natural features to which distances or directions, or both, from the corner or monument are known. Accessories are part of the monument, and in the absence of the monument, may carry the same weight.
Problems are best solved by putting the problem in the right category and applying the appropriate rules, which may vary depending on the category. When it comes to corners, the rules do vary, and misidentifying the type of corner may lead to applying the wrong rule(s). That, in turn, may lead to disastrous results, at the least affecting the title to the land.
About the Author
Don Wilson is president of Land & Boundary Consultants, Inc.; and part owner of and the lead instructor in Surveyors Educational Seminars, a member of the Professional Surveyor/ RedVector Dream Team providing online courses for continuing education; and a regular instructor in the University of New Hampshire Continuing Education System for 25 years. He is also co-author of several well-known texts.
Rules of the Game: Types of Corners
Donald A. Wilson, LLS, PLS, RPF
Since there sometimes seems to be some confusion as to what corners really are, perhaps further clarification is in order. The court system has provided considerable insight. In the previous article, a definition was presented. This article will focus on the different types of corners that might be encountered.
Care should be taken when discussing corners, as there are many types. There are property corners, but also street corners, building corners, and fence corners, which may or may not be property corners, depending upon the circumstances.
Classifications of Corners
A corner, according to the Tennessee court, may be defined as the intersection of two converging lines or surfaces; an angle, whether internal or external; as the "corner" of a building, the four "corners" of a square, the "corner" of two streets. A mere variation in a line does not constitute a "corner" (Christian v. Gernt, et al., 64 S.W. 399 [Tenn. Ch., 1900]). In this case, the court was quoting from the Century Dictionary. One of the parties insisted that a particular point was a corner, whereupon the court, relying on the above definition, stated that it cannot be a corner but is a mere variation in the line.
Closing corner: a corner at the intersection of a surveyed boundary with a previously established boundary line. In the survey of the public land of the United States, when a line connecting the last section corner and the objective corner on an established township boundary departs from the astronomic meridian by more than an allowable deviation, the line being surveyed is projected on cardinal to an intersection with the township boundary, where a closing corner is established and connection made to the previously established corner (quoted in Lugon v. Crosier, 240 P. 462, 78 Colo. 141 [1925]).
Existent corner: one whose position is identifiable by evidence of monument, its accessories, or description in field notes, or can be located by acceptable supplemental survey record, some physical evidence, or testimony (Manual of Instructions, Bureau of Land Management [1973], quoted in Reid v. Dunn, 20 Cal. Rptr. 273 [1962]). This was addressed in Hartshorn v. Wright, 11 F. 715 (N.J. C.C., 1813), wherein the court addressed an objection that a description was uncertain because the courses of a creek were too indefinite a boundary and that no plot of the land had been produced to show the beginning and course of the western line. The court replied that the language, "'to a spot from whence a south course will strike the beginning,' though not marked by any visible object, is susceptible of precise location by aid of the compass, as there could be but one spot on the margin of the creek, whence a due south course would strike the beginning."
Lost corner: a point of a survey whose position cannot be determined, beyond reasonable doubt, either from traces of the original marks or from acceptable evidence or testimony that bears upon the original position, and whose location can be restored only by reference to one or more interdependent corners (Manual of Instructions, Bureau of Land Management [1973], quoted in Reid v. Dunn, 20 Cal.Rptr. 273 [1962]; U.S. v. Doyle, 468 F.2d 633 [Colo., 1972], paraphrased in Fellows v. Willett, 98 Okla. 248 [1923]).
Meander corner: a corner marking the intersection of a township or section boundary and the mean high-water line of a body of water. Also a corner on a meander line. The Wisconsin court in Thunder Lake Lumber Co. v. Carpenter, 200 N.W. 302, 184 Wis. 580 stated in 1924 that a "meander corner" is not a fixed point for measurements, as are section and quarter corners, but is a marker for courses.
Nonexistent corner: one which has never existed, cannot be said to be lost, obliterated, or established under the rules relating to the establishment of lost or obliterated corners, but should be established at the place where the original surveyor should have put it (Lugon v. Crosier, 240 P. 462, 78 Colo. 141 [1925]). In this case, the court rejected the arguments as to how this corner should be replaced. It concluded that the corner in question is a closing corner, but not one from which a standard parallel has been initiated, nor to which one has been directed. Therefore, the rules do not relate to the question in this case.
If it did, "it cannot be said to be lost or obliterated. It never existed and so cannot, strictly speaking, be said to be lost or obliterated. If the monument were lost or obliterated there would be some reason to attempt to re-locate it, and perhaps the method prescribed in rule 47 is as good a way as any other, but when it is a myth, never on the ground, the natural, straightforward and sensible way is to establish the corner at the place where the original surveyor ought to have put it and that is where the north course of the east line of the section meets the correction line at right angles, and that is where the report puts it. Everybody knows that that is where the section line ought to have closed and where the original surveyor, honest or dishonest, meant to close it; that his duty required him to close it there, so that the enclosure of his lines might be a rectangle or nearly so. Why should courts be less reasonable than reasonable men?"
Obliterated corner: one at whose point there are no remaining traces of the monument or its accessories, but whose location has been perpetuated, or the point for which may be recovered beyond reasonable doubt by the acts and testimony of the interested landowners, competent surveyors, other qualified local authorities, or witnesses, or by some acceptable record evidence (Manual of Instructions, Bureau of Land Management [1973], quoted in Reid v. Dunn, 20 Cal.Rptr. 273 [1962]; U.S. v. Doyle, 468 F.2d 633 [Colo., 1972], paraphrased in Fellows v. Willett, 98 Okla. 248 [1923]).
A property corner is a corner of a parcel of land, right, or interest, which is created by title documents or some mechanism of title creation. It is the point where two property lines intersect.
Quarter corner: a corner of a Quarter Section of land. As distinguished from a section corner, in the government surveys, it means the corner on the section line midway between the section corners (Rud v. Board of County Commissioners of Pope County, 66 Minn. 358 [1896]).
Section corner: a corner of a section of land, or a corner at an extremity of a section line.
Sixteenth corner: a corner of a sixteenth section of land or a quarter-quarter section. It may also be defined as a corner at an extremity of a boundary of a quarter-quarter section, or midpoint between the controlling corners on a section or township boundary.
Standard corner: one that is on a standard parallel or base line.
Township corner: a corner at the extremity of a township boundary or the corner of a township.
Witness corner: by conventional usage, a monumented point usually on a line of the survey and near a corner. It is employed in situations where it is impracticable (or impossible) to occupy the site of a corner. A witness point is a monumented station on a line of a survey and is used to perpetuate an important location more or less remote from and without special relation to any regular corner (Manual of Instructions, Bureau of Land Management [1973]).
Corner accessory: a physical object adjacent to a corner to which the corner is referred for future identification or restoration. Accessories include bearing trees, mounds, pits, ledges, rocks, and other natural features to which distances or directions, or both, from the corner or monument are known. Accessories are part of the monument, and in the absence of the monument, may carry the same weight.
Problems are best solved by putting the problem in the right category and applying the appropriate rules, which may vary depending on the category. When it comes to corners, the rules do vary, and misidentifying the type of corner may lead to applying the wrong rule(s). That, in turn, may lead to disastrous results, at the least affecting the title to the land.
About the Author
Don Wilson is president of Land & Boundary Consultants, Inc.; and part owner of and the lead instructor in Surveyors Educational Seminars, a member of the Professional Surveyor/ RedVector Dream Team providing online courses for continuing education; and a regular instructor in the University of New Hampshire Continuing Education System for 25 years. He is also co-author of several well-known texts.
domingo, 4 de mayo de 2008
Conversion tables: Will be unscrambled in time
APPENDIX C
UNITS OF MEASURE AND CONVERSION FACTORS
This appendix provides conversion tables for units of measure and conversion factors that are used in military operations.
12 inches
36 inches
3 feet
1,760 yards
2,026.8 yards
5,280 feet
6,080.4 feet
63,360 inches
72,963 inches
=
=
=
=
=
=
=
=
=
1 foot
1 yard
1 yard
1 mile statute
1 mile nautical
1 mile statute
1 mile nautical
1 mile statute
1 mile nautical
Table C-1. English system of linear measure.
1 millimeter
10 millimeters
10 centimeters
10 decimeters
10 meters
10 decameters
10 hectometers
10 kilometers
=
=
=
=
=
=
=
=
centimeter
centimeter
decimeter
meter
decameter
hectometer
kilometer
1.0 myriameter
=
=
=
=
=
=
=
=
0.0393 inches
0.3937 inches
3.937 inches
39.37 inches
32.81 feet
328.1 feet
0.62 mile
6.21 miles
Table C-2. Metric system of linear measure.
1 mil
1 grad
1 degree
=
=
=
1/6400 circle
1/400 circle
1/360 circle
=
=
=
0.05625°
16.0 mils
about 17.8 mils
=
=
=
0.0625 grad
0°54' = 0.9°
about 1.1 grad
Table C-3. Equivalent units of angular measure.
ONE
INCHES
FEET
YARDS
STATUTE MILES
NAUTICLE MILES
mm
Inch
1
0.0833
0.0277
-
-
25.40
Foot
12
1
0.333
-
-
304.8
Yard
36
3
1
0.00056
-
914.4
Statute Mile
63,360
5,280
1,760
1
0.8684
-
Nautical Mile
72,963
6,080
2,026
1.1516
1
-
Millimeter
0.0394
0.0033
0.0011
-
-
1
Centimeter
0.3937
0.0328
0.0109
-
-
10
Decimeter
3.937
0.328
0.1093
-
-
100
Meter
39.37
3.2808
1.0936
0.0006
0.0005
1,000
Decameter
393.7
32.81
10.94
0.0062
0.0054
10,000
Hectometer
3,937
328.1
109.4
0.0621
0.0539
100,000
Kilometer
39,370
3,281
1,094
0.6214
0.5396
1,000,000
Myriameter
393,700
32,808
10,936
6.2137
5.3959
10,000,000
ONE
cm
dm
M
dkm
hm
km
mym
Inch
2.540
0.2540
0.0254
0.0025
0.0003
-
-
Foot
30.48
3.048
0.3048
0.0305
0.0030
0.0003
-
Yard
91.44
9.144
0.9144
0.0914
0.0091
0.0009
-
Statute Mile
160,930
16,093
1,609
160.9
16.09
1.6093
0.1609
Nautical Mile
185,325
18,532
1,853
185.3
18.53
1.8532
0.1853
Millimeter
0.1
0.01
0.001
0.0001
-
-
-
Centimeter
1
0.1
0.01
0.001
0.0001
-
-
Decimeter
10
1
0.1
0.01
0.001
0.0001
-
Meter
100
1
1
0.1
0.01
0.001
0.0001
Decameter
1,000
10
10
1
0.1
0.01
0.001
Hectometer
10,000
100
100
10
1
0.1
0.01
Kilometer
100,000
1,000
1,000
100
10
1
0.1
Myriameter
1,000,000
10,000
10,000
1000
100
10
1
Table C-4. Conversion factors.
Example I
Problem:
Reduce 76 centimeters to (?) inches.76 cm x 0.3937 = 29 inches
Answer:
There are 29 inches in 76 centimeters.
Example II
Problem:
How many feet are there in 2.74 meters?
2.74
=
9 feet
——
.3048
Answer:
There are approximately 9 feet in 2.74 meters.
SCALE
1 INCH EQUALS
1 CENTIMETER EQUALS
1:5,000
416.67 feet127.00 meters
164.00 feet50.00 meters
1:10,000
833.33 feet254.00 meters
328.10 feet100.00 meters
1:12,500
1,041.66 feet317.00 meters
410.10 feet125.00 meters
1:20,000
1,666.70 feet508.00 meters
656.20 feet200.00 meters
1:25,000
2,083.30 feet635.00 meters
820.20 feet250.00 meters
1:50,000
4,166.70 feet1,270.00 meters
1,640.40 feet500.00 meters
1:63,360
5,280.00 feet1,609.30 meters
2,078.70 feet633.60 meters
1:100,000
8,333.30 feet2,540.00 meters
3,280.80 feet1,000.00 meters
1:250,000
20,833.00 feet6,350.00 meters
8,202.00 feet2,500.00 meters
1:500,000
41,667.00 feet12,700.00 meters
16,404.00 feet5,000.00 meters
Table C-5. Ground distance at map scale.
UNITS OF MEASURE AND CONVERSION FACTORS
This appendix provides conversion tables for units of measure and conversion factors that are used in military operations.
12 inches
36 inches
3 feet
1,760 yards
2,026.8 yards
5,280 feet
6,080.4 feet
63,360 inches
72,963 inches
=
=
=
=
=
=
=
=
=
1 foot
1 yard
1 yard
1 mile statute
1 mile nautical
1 mile statute
1 mile nautical
1 mile statute
1 mile nautical
Table C-1. English system of linear measure.
1 millimeter
10 millimeters
10 centimeters
10 decimeters
10 meters
10 decameters
10 hectometers
10 kilometers
=
=
=
=
=
=
=
=
centimeter
centimeter
decimeter
meter
decameter
hectometer
kilometer
1.0 myriameter
=
=
=
=
=
=
=
=
0.0393 inches
0.3937 inches
3.937 inches
39.37 inches
32.81 feet
328.1 feet
0.62 mile
6.21 miles
Table C-2. Metric system of linear measure.
1 mil
1 grad
1 degree
=
=
=
1/6400 circle
1/400 circle
1/360 circle
=
=
=
0.05625°
16.0 mils
about 17.8 mils
=
=
=
0.0625 grad
0°54' = 0.9°
about 1.1 grad
Table C-3. Equivalent units of angular measure.
ONE
INCHES
FEET
YARDS
STATUTE MILES
NAUTICLE MILES
mm
Inch
1
0.0833
0.0277
-
-
25.40
Foot
12
1
0.333
-
-
304.8
Yard
36
3
1
0.00056
-
914.4
Statute Mile
63,360
5,280
1,760
1
0.8684
-
Nautical Mile
72,963
6,080
2,026
1.1516
1
-
Millimeter
0.0394
0.0033
0.0011
-
-
1
Centimeter
0.3937
0.0328
0.0109
-
-
10
Decimeter
3.937
0.328
0.1093
-
-
100
Meter
39.37
3.2808
1.0936
0.0006
0.0005
1,000
Decameter
393.7
32.81
10.94
0.0062
0.0054
10,000
Hectometer
3,937
328.1
109.4
0.0621
0.0539
100,000
Kilometer
39,370
3,281
1,094
0.6214
0.5396
1,000,000
Myriameter
393,700
32,808
10,936
6.2137
5.3959
10,000,000
ONE
cm
dm
M
dkm
hm
km
mym
Inch
2.540
0.2540
0.0254
0.0025
0.0003
-
-
Foot
30.48
3.048
0.3048
0.0305
0.0030
0.0003
-
Yard
91.44
9.144
0.9144
0.0914
0.0091
0.0009
-
Statute Mile
160,930
16,093
1,609
160.9
16.09
1.6093
0.1609
Nautical Mile
185,325
18,532
1,853
185.3
18.53
1.8532
0.1853
Millimeter
0.1
0.01
0.001
0.0001
-
-
-
Centimeter
1
0.1
0.01
0.001
0.0001
-
-
Decimeter
10
1
0.1
0.01
0.001
0.0001
-
Meter
100
1
1
0.1
0.01
0.001
0.0001
Decameter
1,000
10
10
1
0.1
0.01
0.001
Hectometer
10,000
100
100
10
1
0.1
0.01
Kilometer
100,000
1,000
1,000
100
10
1
0.1
Myriameter
1,000,000
10,000
10,000
1000
100
10
1
Table C-4. Conversion factors.
Example I
Problem:
Reduce 76 centimeters to (?) inches.76 cm x 0.3937 = 29 inches
Answer:
There are 29 inches in 76 centimeters.
Example II
Problem:
How many feet are there in 2.74 meters?
2.74
=
9 feet
——
.3048
Answer:
There are approximately 9 feet in 2.74 meters.
SCALE
1 INCH EQUALS
1 CENTIMETER EQUALS
1:5,000
416.67 feet127.00 meters
164.00 feet50.00 meters
1:10,000
833.33 feet254.00 meters
328.10 feet100.00 meters
1:12,500
1,041.66 feet317.00 meters
410.10 feet125.00 meters
1:20,000
1,666.70 feet508.00 meters
656.20 feet200.00 meters
1:25,000
2,083.30 feet635.00 meters
820.20 feet250.00 meters
1:50,000
4,166.70 feet1,270.00 meters
1,640.40 feet500.00 meters
1:63,360
5,280.00 feet1,609.30 meters
2,078.70 feet633.60 meters
1:100,000
8,333.30 feet2,540.00 meters
3,280.80 feet1,000.00 meters
1:250,000
20,833.00 feet6,350.00 meters
8,202.00 feet2,500.00 meters
1:500,000
41,667.00 feet12,700.00 meters
16,404.00 feet5,000.00 meters
Table C-5. Ground distance at map scale.
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